Burundian students broke into the U.S. embassy to escape police Thursday as one of the country's vice presidents announced he had fled to Belgium, escalating a political crisis in the central African nation days before key elections.

Ignoring armed U.S. Marines watching from the roof of the US mission, around 200 students climbed under the gate and over the wall before sitting inside the compound with their hands raised.

Burundi's government on Wednesday joined a fresh round of U.N.-led talks hoped to broker peace between rival parties following weeks of violence and ahead of elections on Monday.

It comes one day after the ruling CNDD-FDD party slammed the talks as a diversion "aimed to disrupt the elections."

Burundi's ruling party said Tuesday it had boycotted the restart of U.N.-led talks hoped to broker peace between rival parties following weeks of violence and ahead of elections on Monday.

The troubled central African nation has been in crisis since late April over President Pierre Nkurunziza's controversial bid to stand for a third consecutive five-year term.

Burundi's government and opposition on Monday traded blame for grenade attacks that killed four people and wounded around 30 in ongoing violence a week ahead of key parliamentary elections.

The troubled central African nation has been in crisis since late April over President Pierre Nkurunziza's controversial bid to stand for a third consecutive five-year term, a move branded by opponents as unconstitutional and a violation of a 2006 peace deal that ended 13 years of civil war.

Eleven Burundian police officers were wounded, one of them seriously, in a string of overnight grenade attacks in the capital of the crisis-hit central African nation, security sources said Saturday.

"Last night, several police posts as well as police vehicles were attacked with grenades. Eleven police officers were wounded, one of them seriously, and police responded with sustained gunfire," a senior police official told Agence France Presse, blaming demonstrators opposed to President Pierre Nkurunziza's controversial bid for a third term in office.

At least 70 people have been killed, 500 wounded and over 1,000 jailed in weeks of political violence in Burundi, a rights groups said late Thursday.

The troubled central African nation has been in crisis since late April over President Pierre Nkurunziza's controversial bid to stand for a third consecutive five-year term, a move branded by opponents as unconstitutional and a violation of a 2006 peace deal that ended 13 years of civil war.

Burundi's government said Thursday it had agreed "in principle" to the deployment of African Union military observers and human rights experts to monitor key elections following weeks of political unrest.

But Burundi rejected AU calls for further delays to the polls, with parliamentary elections planned for June 29, ahead of the presidential vote on July 15.

African leaders meeting at a summit in Johannesburg on Monday agreed to send military experts to Burundi, which has been rocked by weeks of violence over the president's controversial bid for a third term.

Since surviving a coup attempt last month President Pierre Nkurunziza has faced down international pressure to reconsider his attempt to stay in power, which diplomats fear could plunge the country into war.

Burundi's opposition late Friday slammed the election commission for steering the country towards a controversial presidential vote next month, branding it a tool of President Pierre Nkurunziza and his ruling party.

The appointment of two new members to the national election commission (CENI) was "a government-orchestrated sham to put in place a CENI totally subservient to Nkurunziza and his party", said Jeremie Minani, spokesman for the Arusha Movement coalition of opposition and civil society groups.

Burundi's opposition parties have threatened to boycott elections later this month if the government fails to create the conditions for a fair vote, a spokesman for a coalition of 17 parties said Friday.

The troubled central African nation has been in crisis since late April over President Pierre Nkurunziza's controversial bid to stand for a third consecutive five-year term, a move branded by opponents as unconstitutional and a violation of a 2006 peace deal that ended 13 years of civil war.